Migratory Bird Day (IMBD)
Migration Can be Difficult and Dangerous, but Billions of Birds do it Twice Each Year
May 3, 2006
International Migratory Bird Day (IMBD) raises awareness of a global phenomenon that needs protection - the annual migration of vast numbers of birds. This year, the theme for IMBD is "The Boreal Forest: Bird Nursery of the Americas." The boreal forest, stretching across Canada, is the summer destination for billions of migrating birds.
In the most visible migrations, birds travel from the higher latitudes in the north and south to distant warmer latitudes each year: a map of the known flyways looks like a busy highway map where all routes ultimately run north-south. Some birds, however, simply move between higher and lower altitudes in the same geographic location.
Migration happens mainly because of the weather. When days grow shorter with approaching winter and food supplies dwindle, birds start moving to warmer places. In the spring, they return to cooler summer ranges to mate and raise their young. It's amazing to us that birds can find their way, time after time, to specific places so far apart: migrating birds are guided by the Sun and stars, Earth's magnetic field, sight, and sound.
Migration is dangerous. Birds are killed by collisions, extreme weather, predators, hunters, pollution, and starvation. Sometimes they arrive at a critical stopover to find it gone, a city suburb, farm, or clear-cut in its place. Because bird species need habitat in different countries along their routes, the struggle to protect them requires international cooperation.
Here are some bird migration facts from the Firefly Encyclopedia of Birds (Firefly Books, 2003):
- The Eastern Red-footed Falcon migrates about 30,000 kilometers (more than 18,000 miles) from China to southern Africa.
- The Bar-tailed Godwit may migrate from Alaska to New Zealand without stopping.
- Emus generally lead solitary lives, but gather in large groups and migrate when food becomes scarce.
- Ultra light aircraft, manned by humans dressed in crane costumes, are being used to teach young cranes raised in captivity how to migrate.
- In Europe, crossbills occasionally "irrupt" out of their normal range - huge numbers of these birds migrate into new territory searching for food and sometimes damaging crops.
- Migrating pittas fly by night and tend to be attracted to lights, resulting in lethal collisions with windows and other light sources.
- Swallows migrate at low altitudes while some migrating cranes and birds of prey fly at altitudes higher than the summit of Mount Everest.
- An Alpine swift can travel more than 500 kilometers (about 300 miles) in a day.
The Canadian Wildlife Federation is celebrating International Migratory Bird Day on May 13: there are many IMBD events planned on the weekend of May 13 and 14 in locations all across the United States and Canada. The date's not cast in stone, however, and some places set a different date depending on local birds.
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